Field of the Invention
The present invention relates generally to a small, precision, passive one-way valve for medical applications which opens when a minimal pressure drop occurs across the valve, and more particularly to an improved valve for use in a medical infusion pump, which improved valve may be installed in a flat-top configuration allowing the portion of the housing on top of the valve to be flat rather than precision contoured, thereby allowing substantial reduction in the cost of the pump.
In the past there have been two techniques used to deliver drugs which may not be orally ingested to a patient. The first such technique is through an injection, or shot, which delivers a large dosage at relatively infrequent intervals to the patient. This technique is not always satisfactory, particularly when the drug being administered is lethal or has negative side effects when delivered in a large dosage. This problem results in smaller injections being given at more frequent intervals.
Alternatively, the second technique involves administering a continuous flow of medication to the patient through an IV bottle. Medication may also be delivered through an IV system with an injection being made into a complex maze of IV tubes, hoses, and other paraphernalia. As an alternative to these two techniques of administering medication to a patient, the recent addition of medication infusion pumps has come as a welcome improvement.
Infusion pumps are utilized to administer drugs to a patient in small, metered doses at frequent intervals or, alternatively, in the case of some devices, at a low but essentially continuous rate. Infusion pump therapy may be electronically controlled to deliver precise, metered doses at exactly determined intervals, thereby providing a beneficial gradual infusion of medication to the patient. In this manner, the infusion pump is able to mimic the natural process whereby chemical balances are maintained precisely by operating on a continuous time basis.
One of the essential elements of an infusion pump is a one-way valve, one or more of which is required in virtually any design for an infusion pump. Such a valve must be highly precise, operating in a passive manner to open with a relatively small break pressure or cracking pressure in the desired direction of flow through the valve. The valve must also be resistant to a substantially higher reverse pressure, not opening or leaking at all, since any reverse flow in the opposite direction would result a reduction in the amount of medication being delivered, and an imprecise infusion pump which would be totally unacceptable.
The valve must be easily manufactured, and must have both an extended shelf life and a long operating life. It must also be made from a material which is of a medical grade, and which will not be affected by any of the numerous medications which may be administered by the infusion pump.
An additional requirement has been imposed by the important design consideration of disposability. It is desirable that the pump portion of the infusion pump device be disposable, and therefore the valve must in addition to all the requirements previously mentioned be inexpensive, and must also be installable in the pump easily. Since the inexpensive nature of the disposable pump mandates against expensive molding techniques, it is a primary object of the valve that it be installable in the pump with only one half of the housing containing the valve requiring a complex form. More specifically, the top or inlet portion of the housing will be flat save for an opening through which the medication being pumped may flow into contact with and through the valve.
It is also necessary in order to minimize the number of parts required and therefore the cost of construction of the disposable pump that sealing means be included in the integral design of the pump. When the two portions of the pump housing are assembled with the valve therebetween, fluid will be able to flow only through the valve, and not around it. In addition, leaks from the pump between the two portions of the housing will be prevented by the sealing means.